Loader With Lifting Arrangement

ABSTRACT

A loader includes a frame arrangement with a front frame portion and a rear frame portion. The loader includes a lifting arrangement mounted to the front frame portion. The lifting arrangement comprises a main arm provided with a pivot connector at a proximate end and an equipment connector at a distal end. The lifting arrangement includes a main arm support means for pivotably supporting the pivot connector of the main arm. The main arm support means is movable in a direction including a component in a front-rear direction with respect to the front frame portion. The lifting arrangement includes a main arm actuating element for pivoting the main arm such that the equipment connector is movable between a lowered position and a lifted position.

TECHNICAL FIELD

The present invention relates to a loader with a rear frame portion, to which an operator's cab is mounted, and a front frame portion, which supports a lifting arrangement. The lifting arrangement may be a vertical lifting arrangement for moving an equipment between a lowered and a lifted position along a substantially vertical path.

BACKGROUND OF THE INVENTION

Loaders usually comprise a front-mounted bucket to scoop up loose material from the ground, such as dirt, sand or gravel, and move it from one place to another without pushing the material across the ground. Loaders may be used to move a stockpiled material from ground level and deposit it into an awaiting dump truck.

Said loaders usually comprise a lifting arrangement for moving the bucket from a lowered position to a lifted position. Conventional lifting arrangements comprise a main arm with a pivot connector, which is mounted to the loader frame, and an equipment connector for mounting a bucket thereto. Upon moving the main arm between a lowered position and a lifted position, the equipment connector follows a substantially arcuate path, as the main arm is rotated around a point, which is fixed in space relative to the frame arrangement of the loader. Such lifting arrangements are known as radial lifting arrangements.

Recently, vertical lifting arrangements for loaders have been proposed. Said vertical lifting arrangements comprise a main arm support means, which is pivotably mounted to the machine frame of the loader, and a main arm with a pivot connector, which is mounted to the main arm support means. The main arm support means allows for an adjustment of the point of rotation of the main arm to provide movement paths of the equipment connector between lowered and lifted positions that deviate from an arcuate path. Such vertical lifting arrangements are known from WO 2016/123732 A1 and WO 2016/123735 A1.

SUMMARY OF THE INVENTION

The present invention relates to a loader having a frame arrangement with a front frame portion and a rear frame portion. The front frame portion and the rear frame portion may be regions of a single component. Alternatively, the front frame portion and the rear frame portion may be separate components or parts, which may be connected to each other. The connection may be configured such that said two parts are movable with respect to each other. The front frame portion is situated forward of the rear frame portion in forward moving direction of the loader. The front frame portion may support front wheels and/or the rear frame portion may support rear wheels of the loader. Additionally or alternatively, the loader may be a tracked loader. The front frame portion may support front tracks and/or the rear frame portion may support rear tracks of the loader. Furthermore, the front and rear frame portions of the loader may together support a single pair of tracks.

The loader comprises an operator's cab mounted to the rear frame portion. Optionally, the operator's cab is mounted to the rear frame portion in a non-movable manner. The operator's cab may comprise a front wall element, two side wall elements and/or a rear wall element. At least one of said wall elements, e.g. one of said side wall elements, may constitute or may comprise a door for entering the cab. The cab may house an operator's seat and controls for operating the loader. The controls may include controls for operating working hydraulics and/or controls for steering and/or controls for driving of the loader.

The loader may comprise a longitudinal symmetry axis. The longitudinal symmetry axis may be oriented in the movement direction of the loader when the same is moved straight forward, and may be oriented in parallel to the ground plane, i.e. the contact plane of the wheels and/or tracks of the loader with the ground. The longitudinal symmetry axis may exhibit symmetry with respect to the design of the loader, in particular with respect to the wheels and/or tracks when the loader is moved straight forward. The lifting arrangement and/or one or multiple part(s) thereof may exhibit symmetry or may be provided asymmetric with respect to said longitudinal symmetry axis. A longitudinal direction of the loader is aligned to the longitudinal symmetry axis, a lateral direction of the loader is oriented perpendicular to the longitudinal symmetry axis and parallel to the ground plane. A vertical or height direction of the loader is oriented normally to the ground plane.

The operator's cab comprises a front window. The front window may be provided at the front wall element. The front window may exhibit curvature or may be completely plane. The longitudinal symmetry axis of the loader may be oriented at a 90° angle to the front window when the loader is moved straight forward. Optionally, said longitudinal symmetry axis is oriented normally to the front window when the loader is moved straight forward. The front window comprises a lower boundary. The lower boundary delimits the front window downwards, i.e. towards the ground. The lower boundary extends along the entire front window in lateral direction of the loader. The design of the lower boundary may exhibit symmetry with respect to the longitudinal symmetry axis of loader.

In addition, the loader comprises a lifting arrangement, which is mounted to the front frame portion. The lifting arrangement comprises a main arm, which is provided with a pivot connector at a proximate end thereof and an equipment connector at a distal end thereof. An equipment, e.g. a bucket and/or a fork, can be mounted to the equipment connector. Furthermore, the lifting arrangement comprises a main arm support means for pivotably supporting said pivot connector of said main arm. The main arm may be pivotably mounted to the main arm support means via the pivot connector. Further, the main arm support means may be pivotably mounted to the front frame portion of the loader, e.g. to a machine frame of the front frame portion. The main arm support means is movable in a direction, which includes at least a component in the front-rear direction with respect to said front frame portion.

In addition, the lifting arrangement comprises a main arm actuating element for pivoting said main arm to move said equipment connector between a lowered position and a lifted position. The lowered position in the context of the present invention is preferably the lowest position of the equipment connector in normal operating conditions of the lifting arrangement. Further, the lifted position of the equipment connector is preferably the highest position of the equipment connector in normal operating conditions of the lifting arrangement. Via the main arm support means, the point of rotation of the main arm may be adapted to provide movement paths of the equipment connector between the lowered position and the lifted position that deviate from an arcuate path. For example, a substantially vertical movement path may be realized. A substantially vertical path may comprise vertical, J-shaped and/or section of different curvature. The substantially vertical path may be a J-shaped path, in which the equipment connector may be moved, from the lowered to the lifted position, upward and forward in an initial lifting phase and then substantially only upward. A substantially vertical path in the context of the present invention is a path that is overall of vertical nature having regard to the present context. The path might have deviations from a strict vertical path, which do not affect the substantially vertical nature thereof. In other words, a substantially vertical path is not a substantially arcuate path.

The loader according to the present invention is configured such that the pivot connector of the main arm is situated below at least a section of the lower boundary of the front window in an operating position of the lifting arrangement. In other words, in a direction normal to the ground, i.e. the vertical direction of the loader, the pivot connector is situated below at least a section of the lower boundary of the front window in said operating position. Thus, in said operating position, said pivot connector is closer to the ground than said section of the lower boundary. This is achieved by matching the geometric designs of the operator's cab with the front window as well as the lifting arrangement to each other in such a way that the above described geometric relationship is fulfilled at said operating position.

The present invention provides a loader with a lifting arrangement that allows for non-arcuate lifting paths, the loader providing good visibility for an operator. Specifically, by moving the main arm support means mainly in a region below the lower boundary of the front window, it does not significantly enter the view through the font window, therefore not deteriorating visibility.

According to an embodiment, the loader is configured such that the pivot connector is situated below said section of the lower boundary of the front window in an intermediate position of the lifting arrangement. In the intermediate position of the lifting arrangement, the main arm, e.g. a line running through the pivot connector and the equipment connector, is oriented horizontally, i.e. in parallel to the ground. This embodiment provides a good compromise between visibility and other machine specifications, e.g. dump height and dump reach.

The pivot connector may be situated below said section of the lower boundary of the front window in all operating positions of the lifting arrangement. In other words, while pivoting the lifting arrangement from the lowered position to the lifted position, the pivot connector stays below said section of the lower boundary at all times. This embodiment provides a loader with very good visibility as the pivot connector never moves into the view through the front window. Additionally or alternatively, the pivot connector may be situated below the entire lower boundary of the front window at a single or all operating positions of the lifting arrangement. This also leads to an improved visibility.

According to an embodiment, the entire main arm support means is situated below said section of the lower boundary of the front window in the intermediate position. Thus, no parts of the main arm support means deteriorate the view of an operator.

The front frame portion and the rear frame portion of the loader may be articulatingly interconnected for providing an articulating steering. The articulating steering may be provided by an articulating support and one or multiple steering actuators, e.g. hydraulic actuators, which may effect a relative displacement of front and rear frame portions with respect to each other. The loader may be a wheel loader.

Furthermore, according to an embodiment, the lifting arrangement comprises a guiding means engaged to said main arm at a guided portion of said main arm positioned between said pivot connector and said equipment connector, wherein upon pivoting said main arm between said lowered position and said lifted position, said guiding means guides the main arm such that said equipment connector follows a predetermined path. This embodiment allows for the provision of a non-arcuate lifting path in a strictly mechanical and thus robust way.

Alternatively, the non-arcuate lifting path may be provided by an auxiliary actuating element engaged to said main arm and said main arm support means for adjusting an angle therebetween, a determining means for determining a lifting related quantity reflecting a position of said equipment connector with respect to said frame arrangement, and a control means for controlling an operation of said main arm actuating element and said auxiliary actuating element based on the determined lifting related quantity. The control of the actuating element can be such that a path of said equipment connector upon moving between said lowered and said lifted positions follows a predetermined path. This embodiment allows for the provision of a variety of non-arcuate lifting path with a single machine.

According to an embodiment, the lifting arrangement is configured to move the equipment connector between said lowered and said lifted positions along a substantially vertical path. This reduces the maximal distance of the equipment connector to the construction machine's centre of gravity upon moving an equipment between said lowered and said lifted positions. Thus, for a given operating weight of the machine, maximal lifting capacity can be increased.

According to an embodiment, the operator's cab comprises an operator's seat, which is aligned to the front window. The alignment can be such that an operator when sitting on the operator's seat in an intended fashion is oriented to look straight ahead through the center of the front window without turning his body or moving his head or eyes. The loader may be configured such that the pivot connector is situated outside of the foveal field of vision of the operator sitting on the operator's seat in the above described intended fashion in all operating positions of the lifting arrangement. In the context of the present invention, the field of vision of the operator may be understood as the region that can be seen by the operator while keeping his head static and looking straight ahead without moving his eyes. The foveal field of vision may be that part of the field of vision that can be seen sharply. The operator may be an operator of average height. The operator may have a height between 1.50 m and 2.10 m, e.g. between 1.70 m and 1.95 m. This embodiment provides good visibility as the pivot connector does not enter the foveal field of vision of the operator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side view of a loader with a lifting arrangement according to an embodiment of the invention in a lowered position.

FIG. 2 illustrates a side view of the loader of FIG. 1 in an intermediate position.

FIGS. 3a-3c schematically illustrate the front window and the lifting arrangement of the loader of FIGS. 1-2 from the perspective of an operator.

FIGS. 4a-4c illustrate the lifting arrangement of FIGS. 1-3 in different positions for explaining its functionality.

FIGS. 5a-5c illustrate an alternative configuration of the lifting arrangement with which the loader of FIGS. 1-3 can be equipped in different positions for explaining its functionality.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a loader 1 according to the present invention in a simplified side view. Elements which are not essential for the invention are omitted. The loader 1 comprises a front frame portion 2 and a rear frame portion 3. A pair of front wheels 4 is mounted to the front frame portion 2 and a pair of rear wheels 5 is mounted to the rear frame portion 3.

An engine compartment 6 is provided at the rear frame portion 3. The engine compartment 6 houses one or multiple power sources for providing power required to operate the loader 1. The power sources can include but are not limited to an internal combustion engine, such as a Diesel engine, which can be coupled to further equipment such as hydraulic pumps, generators and the like. Alternatively or additionally, the power sources can include a battery and an electric engine. The power source is used to provide power for driving the front wheels 4 and/or the rear wheels 5 as well as for providing power for actuators of the construction machine 1. The actuators may be actuators of a lifting arrangement and/or a steering arrangement, for example.

Furthermore, the loader 1 comprises an operator's cab 7 which is mounted to the rear frame portion 3. Inside the operator's cab 7, space for the operator is provided and the required operating and control elements, which are not illustrated are accessible by the operator. The operator's cab 7 comprises an operator's seat, which is not illustrated. The operator's cab 7 comprises a rear wall element 8, two opposing side wall elements 9, which are situated opposite to each other, and a front wall element 12. At least one of the side wall elements 9 comprises a door 11 for accessing the operator's cab 7. The font wall element 12 of the operator's cab 7 comprises a front window 13. In the present embodiment, the front window 13 extends from one side wall element to the other opposite side wall element 9 across the entire lateral direction of the loader 1. The front window 13 is arranged symmetrically with respect to the longitudinal symmetry axis of the loader 1. In the present embodiment, the front window 13 comprises a curved profile in lateral direction.

The front frame portion 2 is mounted to the rear frame portion 3 with an articulating steering arrangement 14. The articulating steering arrangement 14 comprises multiple, optionally two bearings 15, 16, which are situated above each other, for providing an articulating mount between the front frame portion 2 and the rear frame portion 3. A pivoting axis X of the articulating mount, i.e. of the bearings 15, 16, is arranged substantially along the vertical axis of the loader 1. Optionally, the individual pivoting axes of the bearing 15, 16 are coaxial with each other. The steering arrangement 14 can be provided below the operator's cab 7, e.g. directly below the front wall element 12.

The articulating steering arrangement 14 provides a tilting between the front frame portion 2 and the rear frame portion 3 in order to provide a steering by changing the angle between the front frame portion 2 and the rear frame portion 3 in a plane parallel to the ground. The articulating steering arrangement 14 can be driven by one or multiple not illustrated actuator(s), such as hydraulic actuators. Said hydraulic actuators can be driven by a power source of the engine compartment 6. Upon a steering operation, the front frame portion 2 tilts with respect to the rear frame portion 3 and thus the operator's cab 7 and the engine compartment 6, which are provided at the rear frame portion 3.

In addition, the loader 1 comprises a lifting arrangement 17. The lifting arrangement 17 comprises a main arm 18 having a pivot connector 19 at a proximate end and an equipment connector 20 at a distal end thereof. The pivot connector 19 is pivotally supported by a main arm support means 21, which includes a main arm support link in the present embodiment. The main arm support link 21 has a first end and a second end, the first end being pivotably connected to the pivot connector 19 of the main arm 18 and the second end being pivotably connected to an element of the machine frame of the front frame portion 2. The main arm support link 21 is arranged such that a rotation or pivoting movement of the main arm support link 21 provides a movement of the first end in a direction which at least includes a component in the front-rear direction of the construction machine 1.

The main arm 18 comprises a guided portion 22, which is shown in FIGS. 2 and 4 a-4 c and is provided between the pivot connector 19 and the equipment connector 20. In the present embodiment, the guided portion 22 is offset by a predetermined amount from a line connecting the pivot connector 19 and the equipment connector 20. The lifting arrangement 17 further includes a guiding means 23 which includes a guiding arm having a first end and a second end. The first end is pivotably mounted to an element of the front frame portion 2 and the second end is pivotably mounted to the main arm 18 at the guided portion 22.

The lifting arrangement 17 comprises an actuator 24. The actuator 24 has a first end which is pivotably mounted to the front frame portion 2 and a second end which is pivotably mounted to the main arm 18. The actuator 24 is embodied as a linear actuator such as a hydraulic actuator in the present embodiment but not limited thereto. Upon operating the actuator 24, the distance between the first end and the second end can be changed, e.g. by introducing pressurized fluid into pressure chambers of the actuator 24.

Furthermore, at the equipment connector 20 of the main arm 18, a bucket 25 is provided which is an example of an equipment which can be mounted to the main arm 18. The bucket comprises a main arm connector for connection to the equipment connector 20 of the main arm 12 and a tilt connector 26 for tilting the bucket. The tilt connector 26 may be provided above the main arm connector. The tilt connector 26 of the bucket 25 is connected to a tilting arrangement for tilting the bucket 25. The tilting arrangement comprises a lever 27 that is pivotably supported at approximately its centre at the main arm 18. The top end 28 of the lever 27 is connected to a tilt cylinder 29, which is supported at its other end at the main arm 18 in the proximity of the pivot connector 19. The bottom end of the lever 20 is connected via a link, which is not shown, to the tilt connector 26 of the bucket 25. Due to the Z-bar configuration of the tilting arrangement, extending the cylinder 29 results in a bucket rollback and vis versa. However, also other configurations of tilting arrangements are conceivable.

In the following, an operation of the lifting arrangement 17 is explained under reference to the illustrations of FIGS. 4a-4c . In FIG. 4a , the lifting arrangement 17 is illustrated in the lowered position. In this situation, the main arm 18 is rotated downwards. This is achieved by retracting the actuator 24, which is provided for operating the main arm 18. The position of the main arm 18 is determined by the linkage between the guiding arm 23 and the main arm support link 21. In other words, the position of the pivot connector 19 of the main arm 18 can be changed by changing the rotational position of the main arm support link 21, whereas the guiding arm 23 determines, due to its rotational connection between the front frame portion 2 and the guided portion 22 of the main arm 18, the position of the pivot connector 19 depending on the rotational position of the main arm 18. As such, the lifting arrangement provides a link-based transmission which uniquely determines the position of the main arm 18.

Upon actuating the actuator 24, the main arm 18 is rotated in the clockwise direction in FIG. 4a to move it to an position shown in FIG. 4b . With this rotation, the main arm 18 is rotated with respect to the main arm support link 21. At the same time, the guiding arm 23 is rotated in the counter clockwise direction. When the guiding arm 23 rotates in the counter clockwise direction, the guided portion 22 of the main arm 18 is forced along a circular path due to the constant distance between the first and second ends of the guiding arm 23. As can be seen, the position of the second end of the guiding arm 23 has moved with a component of movement in the rearward direction with respect to the loader 1. In the same context, the main arm 18 has rotated in the clockwise direction and the equipment connector 20 has lifted by a predetermined amount. Due to the fact that the guided portion 22 of the main arm 23 is forced in the rearward direction by the predetermined movement path of the second end of the guiding arm 23, the main arm support link 21 is rotated in the clockwise direction about its second end which is mounted to the front frame portion 3. Therefore, the position of the first end of the main arm support link 21 is moved together with the pivot connector 19 of the main arm 18 in the rearward direction with respect to the loader 1.

Upon a further operation of the actuator 24, the main arm 18 is further rotated in the clockwise direction and reaches a lifted position shown in FIG. 4c . In this position, the equipment connector 20 of the main arm 18 has reached a position which is higher than the position shown in FIG. 4b . Upon further rotating the main arm 18 in the clockwise direction, the guiding arm 23 is further rotated in the counterclockwise direction and forces the guided portion 22 of the main arm 18 further along the circular path. As the second end of the guiding arm 23 has moved forward with respect to the position shown in FIG. 4b , the main arm support link 21 is rotated in the counterclockwise direction from the position shown in FIG. 4b . Therefore, the position of the first end supporting the pivot connector 19 of the main arm 18 is further forward compared to the position thereof shown in FIG. 4 b.

Based on the above operation, a bucket 25 can be moved from the lowered position shown in FIG. 4a to the lifted position shown in FIG. 4c through the position shown in FIG. 4b along a substantially vertical path. In particular, the path deviates from an arcuate or circular path which is achievable with radial lifting arrangements in which the pivot connector of the main arm is immovably and stationary with respect to a frame portion of the loader 1.

The lifting arrangement 17 attached to the front frame portion 3 of an embodiment of the present invention can also be configured differently. In the following, a second configuration 30 of the lifting arrangement is explained under reference to FIGS. 5a-5c . Except for the differences outlined below, the lifting arrangement 30 according to this second configuration is configured as that of the first configuration described above. Alike elements are denoted by the same reference signs.

The second configuration of the lifting arrangement 30 does not comprise a guiding arm 23 but instead an auxiliary actuating element 31 embodied as linear actuator. The auxiliary actuating element 31 has a first end and second end, the first end being pivotably mounted to the main arm support link 21. The second end of the auxiliary actuating element 31 is pivotably mounted to the main arm 18. Accordingly, the auxiliary actuating element 31 operates in order to vary the angle of inclination between the main arm support link 21 and the main arm 18. In other words, by extending the auxiliary actuating element 31, the angle enclosed by the main arm support link 21 and the main arm 18 is increased.

The second configuration of the lifting arrangement 30 further comprises a control system and a determining means determining a lifted related quantity reflecting a position of said equipment connector 20 with respect to the front frame portion 2. The determining means can include sensors, which provide information on the extension position of the linear actuators used for the main arm actuating element and the auxiliary actuating element. The type of sensors can be selected as needed as long as it is possible to provide information on the relative position of the main arm 18 with respect to the main arm support link 21 as well as the relative position of the main arm support link 21 with respect to the front frame portion 2. The control system communicates with an output section which is provided for controlling the actuating system of the lifting arrangement, in particular, the main arm actuating element 24 and the auxiliary actuating element 31.

According to the present embodiment, the control system provides a relationship between the movement of the main arm actuating element 24 and the movement of the auxiliary actuating element 31. In other words, a function or pattern included in the control system includes a relationship between the operating position of the main arm actuating element 24 and the operating position of the auxiliary actuating element 31. The relationship can be continuous.

The operation of the control based lifting arrangement is explained in the following. Starting out from the situation in FIG. 5a , the operator manipulates a not illustrated operating element in order to initiate a lifting operation for lifting the equipment connector 20 from a lowered position shown in FIG. 5a to a lifted position shown in FIG. 5c through a position shown in FIG. 5b . With the lifting arrangement 30 shown in FIG. 5a , the main arm actuating element 24 is extended in order to rotate the main arm 18 together with the main arm support link 21 in the clockwise direction in the drawing. In the course of operation of the main arm actuating element 24, the auxiliary actuating element 31 is retracted as can be derived from a comparison of FIG. 5a with FIG. 5b . Based on this retraction of the auxiliary actuating element 31, the angle enclosed between the main arm 18 and the main arm support link 21 is decreased and the pivot connector 19 is withdrawn in the rearward direction with respect to the frame arrangement.

Upon further performing the lifting operation from the position shown in FIG. 5b , the main arm actuating element 24 is further extended in order to further rotate the main arm 18 in the clockwise direction in the drawing. In the course of the lifting operation between the position shown in FIG. 5b towards the lifted position shown in FIG. 5c , the auxiliary actuating element 31 is again extended in order to increase the angle enclosed between the main arm 18 and the main arm support link 21. By this, the pivot connector 19 is moved in the forward direction with respect to the frame arrangement.

Based on the above cooperation of the main arm actuating element 24 and the auxiliary actuating element 31 in combination with the construction using the main arm support link 21, a movement pattern of the equipment connector 20 can be provided which deviates from an arcuate or circular path having a constant radius. Based on the above operation, a bucket can be moved from the lowered position shown in FIG. 5a to the lifted position shown in FIG. 5c through the position shown in FIG. 5b along a substantially vertical path. A closed loop control utilizing the information received from the determining means can be continuously performed by the control system such that there is always a unique relationship between the extension position of the main arm actuating element 24 and the extension position of the auxiliary actuation element 31. Besides the lifting arrangements 17, 30 described above, also alternative lifting arrangements can be provided.

FIGS. 3a-3c schematically show the front window 13 and the lifting arrangement 17 of the loader 1 of FIGS. 1 and 2 at different operating positions of the lifting arrangement 17 from the perspective of an operator sitting inside the operator's cab 7. In FIG. 3a , a lowered, in FIG. 3b an intermediate, and in FIG. 3c a lifted position of the lifting arrangement 17 is illustrated. Alternatively, the loader 1 could comprise a lifting arrangement 30 as illustrated in FIGS. 5a -5 c.

The front window 13 comprises an upper boundary 40, a left side boundary 41, a right side boundary 42, and a lower boundary 43. As derivable from FIGS. 3a-3c , the upper 40 and lower boundaries 43 extend from the left side boundary 41 to the right side boundary 42. In the present embodiment, the upper boundary 42 is completely arranged at a constant height position of the loader 1. In other words, the upper boundary 42 does not exhibit any kind of curvature in the vertical direction of the loader 1. Furthermore, in this embodiment, the two side boundaries are completely arranged at a constant lateral position of the loader 1. In other words, the two side boundaries 42, 43 do not exhibit any kind of curvature in the lateral direction of the loader 1. In this embodiment, the lower boundary 43 is designed symmetrically with respect to the longitudinal symmetry axis of the loader 1. The lower boundary 43 comprises a constant height section 43.1, which completely extends at a constant vertical height of the loader 1. Adjacent the constant height section 43.1, the lower boundary 43 of the front window 13 comprises on each side a recessed section 43.2 and 43.3 for improving visibility of a region below the operator's cab 7. In lateral direction of the loader, the recessed sections 43.2 and 43.3 extend from the constant height section 43.1 to the side boundaries 41 and 42, respectively. Each of the recessed sections 43.2, 43.3 exhibits a profile in the vertical direction of the loader 1 having two line section, which are oriented with respect to each other to form a corner. Accordingly, the recessed sections 43.2, 43.3 of the lower boundary 43 of the front window 13 are not completely situated at a constant vertical height of the loader 1, but exhibit a profile with varying vertical height.

As derivable from FIGS. 3a-3c , the loader 1 according to the present embodiment is configured such that the pivot connector 19 stays below the constant height section 43.1 of the lower boundary 43 of the front window 13 in all operating positions of the lifting arrangement 17 of the loader 1. Accordingly, also the main arm support means 21 stays below the constant height section 43.1 of the front window 13 in all operating positions of the lifting arrangement 17. This is achieved by matching the geometrical designs of the operator's cab 7, e.g. the front wall element 12 with the window 13, and the lifting arrangement 17, 30, e.g. the movement path of the pivot connector 19 and the main arm support means 21, to each other in such a way that said condition is fulfilled. Alternatively, the loader 1 could be configured such that the pivot connector 19 stays below the constant height section 43.1 only at the intermediate position shown in FIG. 3b . It is also conceivable that the loader 1 is configured such that the pivot connector 19 stays below the entire lower boundary 43, i.e. the constant height section 43.1 and the recessed sections 43.2, 43.3, in all operating positions of the lifting arrangement 17, 30. 

1. A loader having a frame arrangement with a front frame portion and a rear frame portion, the loader comprising: an operator's cab mounted to the rear frame portion, the operator's cab having a front window with a lower boundary; and a lifting arrangement mounted to the front frame portion, the lifting arrangement comprising: a main arm having a pivot connector at a proximate end and an equipment connector at a distal end; a main arm support means for pivotably supporting the pivot connector of the main arm, wherein the main arm support means is movable in a direction including at least a component in a front-rear direction with respect to the front frame portion; and a main arm actuating element for pivoting the main arm such that the equipment connector is movable between a lowered position and a lifted position; wherein the loader is configured such that the pivot connector is situated below at least a section of the lower boundary of the front window in an operating position of the lifting arrangement.
 2. The loader according to claim 1, wherein the pivot connector is situated below at least the section of the lower boundary of the front window in an intermediate position of the lifting arrangement in which the main arm is oriented horizontally.
 3. The loader according to claim 1, wherein the pivot connector is situated below at least the section of the lower boundary of the front window in all operating positions of the lifting arrangement.
 4. The loader according to claim 1, wherein the pivot connector is situated below an entire lower boundary of the front window.
 5. The loader according to claim 1, wherein the main arm support means is completely situated below the section of the lower boundary of the front window in the operating position.
 6. The loader according to claim 1, wherein the front frame portion and the rear frame portion are articulatingly interconnected for providing an articulating steering.
 7. The loader according to claim 1, wherein the loader is a wheel loader.
 8. The loader according to claim 1, wherein the lifting arrangement comprises a guiding means engaged to the main arm at a guided portion of the main arm positioned between the pivot connector and the equipment connector, and wherein upon pivoting the main arm between the lowered position and the lifted position, the guiding means guides the main arm such that the equipment connector follows a predetermined path.
 9. The loader according to claim 1, further comprising: an auxiliary actuating element engaged to the main arm and the main arm support means for adjusting an angle therebetween; a determining means for determining a lifting related quantity reflecting a position of the equipment connector with respect to the front frame portion; and a control means for controlling an operation of the main arm actuating element and the auxiliary actuating element based on a determined lifting related quantity; such that a path of the equipment connector upon moving between the lowered position and the lifted position follows a predetermined path.
 10. The loader according to claim 1, wherein the lifting arrangement is configured to move the equipment connector between the lowered position and the lifted position along a substantially vertical path.
 11. The loader according to claim 1, wherein the operator's cab comprises an operator's seat, which aligned to the front window such that an operator looks straight through the front window when sitting on the operator's seat in an intended fashion, wherein the loader is configured such that the pivot connector is situated outside of a foveal field of vision of the operator in all operating positions of the lifting arrangement while the operator is sitting on the operator's seat in the intended fashion. 